Study: Cutting Calories Extends Life

CNN.com

Even older mice on restricted diets fare better in research

WASHINGTON (AP) -- A study in mice suggests that a low-calorie diet
could help extend life even if the dietary change doesn't start until
old age. The study, appearing this week in the Proceedings of the
National Academy of Sciences, showed that mice at the relatively
advanced age of 19 months that were placed on a restricted calorie
diet lived 42 percent longer than litter mates who continued to eat a
standard diet.

Other studies have shown that young mice put on a low-calorie diet
live much longer than mice fed the standard fare. But the new research
suggests that it is never too late to enjoy a life-extension benefit
by reducing calories.
Stephen R. Spindler of the University of California, Riverside, leader
of a team conducting the research, said there is little evidence yet
that dietary restrictions will extend human life, but in mice, at
least, sensible eating even at older ages clearly has a longevity
benefit. He said a 19-month-old mouse is the age equivalent of 60 to
65 years in humans.

Spindler said old mice placed on a restricted calorie diet responded
quickly with better health and that eventually the animals lived up to
six months longer than litter mates fed the standard diet.
If such findings translate to humans, he said, "this could mean a lot
more years and a lot of good years. The mice on caloric restriction
lived longer and they are healthier."

Early vs late start
Spindler said that while older mice that go on a diet do live longer
than those that don't, they still don't live as long as mice that have
been on restricted diets for a lifetime. He said mice put on
low-calorie diets just after birth have been known to live up to four
years, almost twice as long as normal mice and months longer than the
aged mice in the new study.

The message, he said, is that sensible eating for a lifetime is best,
but there are life span benefits even if the diet is not started until
old age. "This is a very important finding," said Dr. George S. Roth
of the National Institute on Aging, one of the National Institutes of
Health. "The dogma has always been that the earlier in life you start
a restricted diet, the better it works for extending life," said Roth,
a researcher studying the aging process who was not involved in
Spindler's research. "This finding suggests that you may get some of
the same benefits starting late in life."

Cancer connection
Spindler said the study also found that the restricted-calorie diets
also slowed the development and advancement of cancer. Death from
tumors is very common among aged mice, he said, but the researchers
found that tumor growth either started later or was slowed among mice
fed limited calories.
The researchers also analyzed how the action of genes changed in mice
placed on restricted calorie diets. Spindler said there were changes
and that these might be biomarkers of how the restricted diet works to
extend life.

"People have been searching for 30 years for biomarkers of the changes
that take place during the aging process," said Spindler. He said the
new study in mice suggests that by measuring the amount and type of
proteins made by the genes scientists could pinpoint the biomarkers of
aging. Once those are known, he said, it would be possible to find
drugs that have the same effect on life extension as
calorie-restricted diets.
Does this mean that eventually aging could be slowed by taking a pill?
"I am confident that that day will come," said Spindler.